Task 1: MAAP5 Development for PAFS (Passive Auxiliary Feedwater System)
a. Development of evaluation model on the temperature and level change of coolant inside the PCCT (Passive Condensation Cooling
Tank) during operation of the PAFS.
- Modeling of PCCT with appropriate nodalization. The model of PCCT, if necessary, can be composed of multi nodes to account
for the natural circulating flow forming around the PCHX in the PCCT.
- Modeling on heat transfer between the PCCT coolant and the PCCT walls.
- Modeling on the vaporizing of the coolant with elevated temperature on the top surface of the cooling pool.
b. Development of evaluation model on the change of fluid phase inside the PCHX tube
- Evaluation capability on heat transfer between the fluid inside the tube experiencing phase change from a single phase to two
phases, that is, from steam to condensate, and the inner surface of the PCHX tube.
- Evaluation capability on heat transfer between the PCCT coolant and the exterior surface of the PCHX Tube
c. Refilling capability of the PCCT cooling water at the inflow rate with range of 230gpm ~ 250gpm when the water level falls below
a set point matching up to the level for preventing exposure of the PCHX tube in the case that the operation of PAFS is continued
over the design life, that is, 8 hours.
Task 2: Review on APR+ MAAP5 Parameters
a. Incorporation of the PAFS model with the existing models.
b. Review of the APR+ MAAP5 parameter in terms of the values of parameters and the containment nodalization scheme.
c. Review of the MAAP5 Analysis
Task 3: Comparison of the MAAP PAFS performance results with those of Experiment (PASCAL Test)
a. The MAAP PAFS model shall be verified with comparing with the results of relevant experiments, PASCAL Test.
b. The comparison shall be performed in the following aspects;
- The following accident sequences shall be considered. A series of possible events in each sequence will be provided
by KEPCO-ENC.
+ Main Steam Line Break (MSLB)
+ Small Break LOCA (SBLOCA)
+ Station Blackout (SBO)
+ Steam generator tube rupture (SGTR)
- The water level in the 2nd side of steam generator
- Mass flow rate and temperature of steam leaving from the main steam piping to the PCHX
- Transients of thermal equilibrium quality along the PCHX tube
- Temperatures on the interior/exterior surfaces of PCHX tube in each node
- Quantities of energy transferred to the PCCT cooling water in each node used for modeling the PCHX
- The water level of condensate returning to the steam generator economizer in the returning piping which is connected to the lower
header of PCHX
- Mass flow rate and temperature of condensate entering into the economizer
- The level and temperature of PCCT cooling water
- Evaluation on the timing that the thermal-hydraulic conditions of RCS fall within the shut down cooling condition, that is, 450 psi
and 350 F.
Task 4: Analysis and documentation of new models and results
a. Provide the results of MAAP5 PAFS model.
- Theoretical and logical mechanism on the MAAP5 PAFS model
- Recommendation on each parameter value for appropriate use of the MAAP5 PAFS model
b. Performance analysis of MAAP5 PAFS model
- Comparison results with those of the relevant experiments (PASCAL)
- Analysis results for each accident sequence
Task 5: Licensing technical support on MAAP5 severe accident analysis
Fauske & Associates, LLC will support the licensing documents and correspondence for MAAP5 PAFS.
Task 6: Technical Meeting
In this task, it is expected the KEPCO E&C two engineers will travel to Fauske & Associates, LLC office for two times meeting. The first visit for technical meeting will occur while Task 1, 2 and 3 are ongoing. The second visit will occur while Task 4 is ongoing. Questions related to the MAAP5 PAFS model and related issues will be discussed.
Task 7: Document of Consultant Results
Fauske & Associates, LLC shall document the results of Tasks 1 to Tasks 4 and related items from the meeting in a Technical Report. A draft will be provided for review prior to final issue.
